They now want to match up drugs with specific stages of the disease.
Experts said it was important to find out if these drugs could work safely in humans.
Statins are taken by people to reduce the risk of developing heart disease and the Cambridge research team says its work may have unearthed a potential "neurostatin" to ward off Alzheimer`s disease.
Genetically programmed worms
Rather than treating the symptoms of the disease, a neurostatin could be used as a preventative measure to stop the condition appearing in the first place.
The cancer drug bexarotene, for example, was found to stop the first step which leads to the death of brain cells in worms genetically programmed to develop Alzheimer`s disease.
In previous trials in humans, researchers tested the drug at a later stage of the disease to see if it would clear amyloid plaques from the brain but the trials were unsuccessful.
Dr Rosa Sancho, head of research at Alzheimer`s Research UK, said scientists must find out exactly how the drug works before any clinical trials.
"We will now need to see whether this new preventative approach could halt the earliest biological events in Alzheimer`s and keep damage at bay in further animal and human studies.
"This early research in worms suggests that bexarotene could act earlier in the process to interfere with amyloid build-up."
Defences `overwhelmed`
Writing in Science Advances, Prof Michele Vendruscolo, senior study author from the University of Cambridge, said the research team wanted to find out more about the mechanics of every stage of the disease`s development.
"The body has a variety of natural defences to protect itself against neurodegeneration, but as we age, these defences become progressively impaired and can get overwhelmed.
"By understanding how these natural defences work, we might be able to support them by designing drugs that behave in similar ways."
Dr Doug Brown, director of research and development at the Alzheimer`s Society, said it was still early days.
"Bexarotene has many side-effects when used to treat lymphoma, such as skin complaints, headaches, and sickness, and we would also need to be sure that it`s safe for people with Alzheimer`s to take.
"We haven`t found any new drugs for dementia in over 10 years, and repurposing drugs that already work for other conditions could provide us with a shortcut to new dementia treatments."
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